These frigid temps will bring out the worst in windows and other issues in a home. Been dealing with this for a lot of years as customers bring up complaints as stated above.
Here is a few things to keep in mind
RH (relative humidity) in a home is is generally kept at 25 to 30%. Non-heating times of the year will require a dehumidifier to reduce the RH. Heating periods will most often use a humidifier such as an Apriaire. When selecting these units, the home owner should verify a few things.
1. The unit is sized according to the volume of their home.
2. Most modern units will have “auto” setting to adjust to the RH to the temperature variance. A huge mistake is often made by the homeowner continually changing the settings in an attempt to get a more intimidate result. Not good!
3. Verify the unit is functioning. Hard water deposits, clogged filters, or failing parts will result in the unit failing. Typically resulting in no moisture or way too much. Do an annual inspection.
Windows – By far are the most common failure in many homes. Unlike an air-sealed/insulated wall, the R values of windows are much less. The R value is just the resistance factor to heat loss. Probably the most over looked aspect of windows is the air infiltration. ALL window frames will have some infiltration. The key is to have the least. Sounds like common sense, but nearly no one ever compares this rating. Low end window manufactures will make it more difficult to locate these numbers.
Your windows are the weakest link and will generally be the coldest part of the exterior envelope. If your getting condensation on your windows, you need to look at a number of factors combined to identify the real issue.
1. Failed frame seal – allows air to infiltrate from exterior to interior or reversed based on the pressure within a home. Some manufacture will sell replacement seals that can be easily and inexpensively reaplaced. Others will have a molded system and the frame seal is not able to be replaced without replacement of the window unit. You will often see condensation or frosting along the edge or in a corner near the frame at the piont of the air leak
Failed gas seal of the window panes. Most commonly a visual trait is fogging or skewed vision through the glass. A commonly unknown situation is the implosion that can happen with these. In extreme cases, the vacuum in the winter time will increase so much that glass will shatter as if someone or something went through it. Most common on a gas leak is condensation developing anywhere on the window. Top, center, sides…. the resistance factor is gone and the cavity between the panes allows for both interior or exterior air to enter.
HVAC supply air – This is a tricky one with new built homes that are well sealed and insulated, but has junk windows. A home with a good R-value will naturally have a furnace that doesn’t cycle as often. Supplies should be placed to the furthest points out in a room, and commonly beneath or near window openings. So as conditioned air travels out, it exchanges with the worst part of the walls (windows) and heats the glass – causing the “dew Point” to be reached at an exterior point rather than interior. Also critical with this is the air exchange. Because the RH can be higher in the more dense cooler air near a window, it needs to be exchanged with the other air of the room to maintain consistency. A solution for this is to set the furnace fan setting to manual or run and allow the fan to operate 24/7 du7ring extreme conditions. This maintains a steady air flow and more consistency in a home.
As mentioned above, cooking, amount of people, pets, all contribute to how much moisture is in the air. During periods of high moisture exchange, run exhaust fans to remove air from the home. In cases when the exterior temps are below zero, the exterior RH is very low, often below 10%. By drawing this air in through your fresh air intake, you will draw the interior RH down. In extreme cases of bioling water for cooking, showers,…. open a window or door for a short period of time. Allowing the super low humidity air in will help reduce the moisture rapidly.
In a case of older homes with poor placement of air supplies, run a ceiling fan or oscillating fan on low to improve air flow/exchange. Open blinds, curtains or other obstructions that prevent warm air from heating the first pane of glass.
